Protein kinases are a family of enzymes that catalyze phosphorylation of proteins, in particular the hydroxyl group of specific tyrosine, serine, or threonine residues in proteins. Protein kinases are pivotal in the regulation of a wide variety of cellular processes, including metabolism, cell proliferation, cell differentiation, and cell survival. Uncontrolled proliferation is a hallmark of cancer cells, and can be manifested by a deregulation of the cell division cycle in one of two ways—making stimulatory genes hyperactive or inhibitory genes inactive. Protein kinase inhibitors, regulators or modulators alter the function of kinases such as cyclin-dependent kinases (CDKs), mitogen activated protein kinase (MAPK/ERK), glycogen synthase kinase 3 (GSK3beta), Checkpoint (Chk) (e.g., CHK-1, CHK-2 etc.) kinases, AKT kinases, PDK-1, JNK, and the like. Examples of protein kinase inhibitors are described in WO02/22610 A1 and by Y. Mettey et al., in J. Med. Chem., 46:222-236 (2003).
The cyclin-dependent kinases are serine/threonine protein kinases, which are the driving force behind the cell cycle and cell proliferation. Misregulation of CDK function occurs with high frequency in many important solid tumors. Individual CDK's, such as, CDK1, CDK2, CDK3, CDK4, CDK5, CDK6 and CDK7, CDK8 and the like, perform distinct roles in cell cycle progression and can be classified as either G1S, or G2M phase enzymes. CDK2 and CDK4 are of particular interest because their activities are frequently misregulated in a wide variety of human cancers. CDK2 activity is required for progression through G1 to the S phase of the cell cycle, and CDK2 is one of the key components of the G1 checkpoint. Checkpoints serve to maintain the proper sequence of cell cycle events and allow the cell to respond to insults or to proliferative signals, while the loss of proper checkpoint control in cancer cells contributes to tumorgenesis. The CDK2 pathway influences tumorgenesis at the level of tumor suppressor function (e.g. p52, RB, and p27) and oncogene activation (cyclin E). Many reports have demonstrated that both the coactivator, cyclin E, and the inhibitor, p27, of CDK2 are either over- or underexpressed, respectively, in breast, colon, nonsmall cell lung, gastric, prostate, bladder, non-Hodgkin's lymphoma, ovarian, and other cancers. Their altered expression has been shown to correlate with increased CDK2 activity levels and poor overall survival. This observation makes CDK2 and its regulatory pathways compelling targets for the development of cancer treatments.
A number of adenosine 5′-triphosphate (ATP) competitive small organic molecules as well as peptides have been reported in the literature as CDK inhibitors for the potential treatment of cancers. U.S. Pat. No. 6,413,974, col. 1, line 23-col. 15, line 10 offers a good description of the various CDKs and their relationship to various types of cancer. Flavopiridol (shown below) is a nonselective CDK inhibitor that is currently undergoing human clinical trials, A. M. Sanderowicz et al., J. Clin. Oncol. 16:2986-2999 (1998).

Other known inhibitors of CDKs include, for example, olomoucine (J. Vesely et al., Eur. J. Biochem., 224:771-786 (1994)) and roscovitine (I. Meijer et al., Eur. J. Biochem., 243:527-536 (1997)). U.S. Pat. No. 6,107,305 describes certain pyrazolo[3,4-b]pyridine compounds as CDK inhibitors. An illustrative compound from the '305 patent is:
K. S. Kim et al., J. Med. Chem. 45:3905-3927 (2002) and WO 02/10162 disclose certain aminothiazole compounds as CDK inhibitors.
Another series of protein kinases are those that play an important role as a checkpoint in cell cycle progression. Checkpoints prevent cell cycle progression at inappropriate times, such as in response to DNA damage, and maintain the metabolic balance of cells while the cell is arrested, and in some instances can induce apoptosis (programmed cell death) when the requirements of the checkpoint have not been met. Checkpoint control can occur in the G1 phase (prior to DNA synthesis) and in G2, prior to entry into mitosis.
One series of checkpoints monitors the integrity of the genome and, upon sensing DNA damage, these “DNA damage checkpoints” block cell cycle progression in G1 & G2 phases, and slow progression through S phase. This action enables DNA repair processes to complete their tasks before replication of the genome and subsequent separation of this genetic material into new daughter cells takes place. Inactivation of CHK1 has been shown to transduce signals from the DNA-damage sensory complex to inhibit activation of the cyclin B/Cdc2 kinase, which promotes mitotic entry, and abrogate G.sub.2 arrest induced by DNA damage inflicted by either anticancer agents or endogenous DNA damage, as well as result in preferential killing of the resulting checkpoint defective cells. See, e.g., Peng et al., Science, 277:1501-1505 (1997); Sanchez et al., Science, 277:1497-1501 (1997), Nurse, Cell, 91:865-867 (1997); Weinert, Science, 277:1450-1451 (1997); Walworth et al., Nature, 363:368-371 (1993); and Al-Khodairy et al., Molec. Biol. Cell., 5:147-160 (1994).
Selective manipulation of checkpoint control in cancer cells could afford broad utilization in cancer chemotherapeutic and radiotherapy regimens and may, in addition, offer a common hallmark of human cancer “genomic instability” to be exploited as the selective basis for the destruction of cancer cells. A number of factors place CHK1 as a pivotal target in DNA-damage checkpoint control. The elucidation of inhibitors of this and functionally related kinases such as CDS1/CHK2, a kinase recently discovered to cooperate with CHK1 in regulating S phase progression (see Zeng et al., Nature, 395:507-510 (1998); Matsuoka, Science, 282:1893-1897 (1998)), could provide valuable new therapeutic entities for the treatment of cancer.
Another group of kinases are the tyrosine kinases. Tyrosine kinases can be of the receptor type (having extracellular, transmembrane and intracellular domains) or the non-receptor type (being wholly intracellular). Receptor-type tyrosine kinases are comprised of a large number of transmembrane receptors with diverse biological activity. In fact, about 20 different subfamilies of receptor-type tyrosine kinases have been identified. One tyrosine kinase subfamily, designated the HER subfamily, is comprised of EGFR (HER1), HER2, HERS and HER4. Ligands of this subfamily of receptors identified so far include epithelial growth factor, TGF-alpha, amphiregulin, HB-EGF, betacellulin and heregulin. Another subfamily of these receptor-type tyrosine kinases is the insulin subfamily, which includes INS-R, IGF-IR, IR, and IR-R. The PDGF subfamily includes the PDGF-alpha and beta receptors, CSFIR, c-kit and FLK-II. The FLK family is comprised of the kinase insert domain receptor (KDR), fetal liver kinase-1(FLK-1), fetal liver kinase-4 (FLK-4) and the fms-like tyrosine kinase-1 (fit-1). For detailed discussion of the receptor-type tyrosine kinases, see Plowman et al., DN&P 7(6):334-339, 1994.
At least one of the non-receptor protein tyrosine kinases, namely, LCK, is believed to mediate the transduction in T-cells of a signal from the interaction of a cell-surface protein (Cd4) with a cross-linked anti-Cd4 antibody. A more detailed discussion of non-receptor tyrosine kinases is provided in Bolen, Oncogene, 8:2025-2031 (1993). The non-receptor type of tyrosine kinases is also comprised of numerous subfamilies, including Src, Frk, Btk, Csk, Abl, Zap70, Fes/Fps, Fak, Jak, Ack, and LIMK. Each of these subfamilies is further sub-divided into varying receptors. For example, the Src subfamily is one of the largest and includes Src, Yes, Fyn, Lyn, Lek, Blk, Hck, Fgr, and Yrk. The Src subfamily of enzymes has been linked to oncogenesis. For a more detailed discussion of the non-receptor type of tyrosine kinases, see Bolen, Oncogene, 8:2025-2031 (1993).
In addition to its role in cell-cycle control, protein kinases also play a crucial role in angiogenesis, which is the mechanism by which new capillaries are formed from existing vessels. When required, the vascular system has the potential to generate new capillary networks in order to maintain the proper functioning of tissues and organs. In the adult, however, angiogenesis is fairly limited, occurring only in the process of wound healing and neovascularization of the endometrium during menstruation. On the other hand, unwanted angiogenesis is a hallmark of several diseases, such as retinopathies, psoriasis, rheumatoid arthritis, age-related macular degeneration, and cancer (solid tumors). Protein kinases which have been shown to be involved in the angiogenic process include three members of the growth factor receptor tyrosine kinase family; VEGF-R2 (vascular endothelial growth factor receptor 2, also known as KDR (kinase insert domain receptor) and as FLK 1); FGF-R (fibroblast growth factor receptor); and TEK (also known as Tie-2).
VEGF-R2, which is expressed only on endothelial cells, binds the potent angiogenic growth factor VEGF and mediates the subsequent signal transduction through activation of its intracellular kinase activity. Thus, it is expected that direct inhibition of the kinase activity of VEGF-R2 will result in the reduction of angiogenesis even in the presence of exogenous VEGF (see Strawn et al, Cancer Res., 56:3540-3545 (1996)), as has been shown with mutants of VEGF-R2 which fail to mediate signal transduction. Millauer et al, Cancer Res., 56:1615-1620 (1996). Furthermore, VEGF-R2 appears to have no function in the adult beyond that of mediating the angiogenic activity of VEGF. Therefore, a selective inhibitor of the kinase activity of VEGF-R2 would be expected to exhibit little toxicity.
Similarly, FGFR binds the angiogenic growth factors aFGF and bFGF and mediates subsequent intracellular signal transduction. Recently, it has been suggested that growth factors such as bFGF may play a critical role in inducing angiogenesis in solid tumors that have reached a certain size. Yoshiji et al., Cancer Research, 57: 3924-3928 (1997). Unlike VEGF-R2, however, FGF-R is expressed in a number of different cell types throughout the body and may or may not play important roles in other normal physiological processes in the adult. Nonetheless, systemic administration of a small molecule inhibitor of the kinase activity of FGF-R has been reported to block bFGF-induced angiogenesis in mice without apparent toxicity. Mohammad et al., EMBO Journal, 17:5996-5904 (1998).
TEK (also known as Tie-2) is another receptor tyrosine kinase expressed only on endothelial cells which has been shown to play a role in angiogenesis. The binding of the factor angiopoietin-1 results in autophosphorylation of the kinase domain of TEK and results in a signal transduction process which appears to mediate the interaction of endothelial cells with peri-endothelial support cells, thereby facilitating the maturation of newly formed blood vessels. The factor angiopoietin-2, on the other hand, appears to antagonize the action of angiopoietin-1 on TEK and disrupts angiogenesis. Maisonpierre et al., Science, 277:55-60 (1997).
The kinase, JNK, belongs to the mitogen-activated protein kinase (MAPK) superfamily. JNK plays a crucial role in inflammatory responses, stress responses, cell proliferation, apoptosis, and tumorigenesis. JNK kinase activity can be activated by various stimuli, including the proinflammatory cytokines (TNF-alpha and interleukin-1), lymphocyte costimulatory receptors (CD28 and CD40), DNA-damaging chemicals, radiation, and Fas signaling. Results from the JNK knockout mice indicate that JNK is involved in apoptosis induction and T helper cell differentiation.
Pim-1 is a small serine/threonine kinase. Elevated expression levels of Pim-1 have been detected in lymphoid and myeloid malignancies, and recently Pim-1 was identified as a prognostic marker in prostate cancer. K. Peltola, “Signaling in Cancer: Pim-1 Kinase and its Partners”, Annales Universitatis Turkuensis, Sarja—Ser. D Osa—Tom. 616, (Aug. 30, 2005), http://kirjasto.utu.fi/julkaisupalvelut/annaalit/2004/D616.html. Pim-1 acts as a cell survival factor and may prevent apoptosis in malignant cells. K. Petersen Shay et al., Molecular Cancer Research 3:170-181 (2005).
Aurora kinases (Aurora-A, Aurora-B, Aurora-C) are serine/threonine protein kinases that have been implicated in human cancer, such as colon, breast and other solid tumors. Aurora-A (also sometimes referred to as AIK) is believed to be involved in protein phosphorylation events that regulate the cell cycle. Specifically, Aurora-A may play a role in controlling the accurate segregation of chromosomes during mitosis. Misregulation of the cell cycle can lead to cellular proliferation and other abnormalities. In human colon cancer tissue, Aurora-A, Aurora-B, Aurora-C have been found to be overexpressed (see Bischoff et al., EMBO J., 17:3052-3065 (1998); Schumacher et al., J. Cell Biol. 143:1635-1646 (1998); Kimura et al., J. Biol. Chem., 272:13766-13771 (1997)).
c-Met is a proto-oncogene that encodes for a tyrosine kinase receptor for hepatocyte growth factor/scatter factor (HGF/SF). The c-Met protein is expressed mostly in epithelial cells, and due to its function it is also known as hepatocyte growth factor receptor, or HGFR. When HGF/SF activates c-Met, the latter in turn may activate a number of kinase pathways, including the pathway from Ras to Raf to Mek to the mitogen-activated protein kinase ERK1 to the transcription factor ETS1. Met signaling has been implicated in the etiology and malignant progression of human cancers (see Birchmeier et al., Nature Reviews Molecular Cell Biology, 4:915-925 (2003); Zhang et al., Journal of Cellular Biochemistry, 88:408-417 (2003); and Paumelle et al., Oncogene, 21:2309-2319 (2002)).
The AGC sub-family of kinases phosphorylate their substrates at serine and threonine residues and participate in a variety of well-known signaling processes, including, but not limited to cyclic AMP signaling, the response to insulin, apoptosis protection, diacylglycerol signaling, and control of protein translation (Peterson et al., Curr. Biol. 1999, 9, R521). This sub-family includes PKA, PKB (c-Akt), PKC, PRK1, 2, p70S6K, and PDK.
AKT (also known as PKB or Rac-PK beta), a serine/threonine protein kinase, has been shown to be overexpressed in several types of cancer and is a mediator of normal cell functions [(Khwaja, A., Nature 1999, 401, 33-34); (Yuan, Z. Q., et al., Oncogene 2000, 19, 2324-2330); (Namikawa, K., et al., J. Neurosci. 2000, 20, 2875-2886,)]. AKT comprises an N-terminal pleckstrin homology (PH) domain, a kinase domain and a C-terminal “tail” region. Three isoforms of human AKT kinase (AKT-1, -2 and -3) have been reported so far [(Cheng, J. Q., Proc. Natl. Acad. Sci. USA 1992, 89, 9267-9271); (Brodbeck, D. et al., J. Biol. Chem. 1999, 274, 9133-9136)]. The PH domain binds 3-phosphoinositides, which are synthesized by phosphatidyl inositol 3-kinase (PI3K) upon stimulation by growth factors such as platelet derived growth factor (PDGF), nerve growth factor (NGF) and insulin-like growth factor (IGF-1) [(Kulik et al., Mol. Cell. Biol., 1997, 17, 1595-1606,); (Hemmings, B. A., Science, 1997, 275, 628-630)]. Lipid binding to the PH domain promotes translocation of AKT to the plasma membrane and facilitates phosphorylation by another PH-domain-containing protein kinases, PDK1 at Thr308, Thr309, and Thr305 for the AKT isoforms 1, 2 and 3, respectively. A second, as of yet unknown, kinase is required for the phosphorylation of Ser473, Ser474 or Ser472 in the C-terminal tails of AKT-1, -2 and -3 respectively, in order to yield a fully activated AKT enzyme.
Once localized to the membrane, AKT mediates several functions within the cell including the metabolic effects of insulin (Calera, M. R. et al., J. Biol. Chem. 1998, 273, 7201-7204) induction of differentiation and/or proliferation, protein synthesis and stress responses (Alessi, D. R. et al., Curr. Opin. Genet. Dev. 1998, 8, 55-62,).
Manifestations of altered AKT regulation appear in both injury and disease, the most important role being in cancer. The first account of AKT was in association with human ovarian carcinomas where expression of AKT was found to be amplified in 15% of cases (Cheng, J. O. et al., Proc. Natl. Acad. Sci. U.S.A. 1992, 89, 9267-9271). It has also been found to be overexpressed in 12% of pancreatic cancers (Cheng, J. O. et al., Proc. Natl. Acad. Sci. U.S.A. 1996, 93, 3636-3641). It was demonstrated that AKT-2 was over-expressed in 12% of ovarian carcinomas and that amplification of AKT was especially frequent in 50% of undifferentiated tumours, suggesting that AKT may also be associated with tumour aggressiveness (Bellacosa, et al., Int. J. Cancer 1995, 64, 280-285).
PKA (also known as cAMP-dependent protein kinase) has been shown to regulate many vital functions including energy metabolism, gene transcription, proliferation, differentiation, reproductive function, secretion, neuronal activity, memory, contractility and motility (Beebe, S. J., Semin. Cancer Biol. 1994, 5, 285-294). PKA is a tetrameric holoenzyme, which contains two catalytic subunits bound to a homo-dimeric regulatory subunit (which acts to inhibit the catalytic sub-units). On binding of cAMP (enzyme activation), the catalytic subunits dissociate from the regulatory subunits to yield the active serine/threonine kinase (McKnight, G. S. et al., Recent Prog. Horm. Res. 1988, 44, pp. 307). Three isoforms of the catalytic subunit (C-α, C-β and C-γ) have been reported to date (Beebe, S. J. et al., J. Biol. Chem. 1992, 267, 25505-25512) with the C-α subunit being the most extensively studied, primarily because of its elevated expression in primary and metastatic melanomas (Becker, D. et al., Oncogene 1990, 5, 1133). To date, strategies to modulate the activity of the C-α subunit involve the use of antibodies, molecules that block PKA activity by targeting regulatory dimers and antisense oligonucleotides expression.
The ribosomal protein kinases p70S6K-1 and -2 are also members of the AGC sub-family of protein kinases and catalyze the phosphorylation and subsequent activation of the ribosomal protein S6, which has been implicated in the translational up-regulation of mRNAs coding for the components of the protein synthetic apparatus. These mRNAs contain an oligopyrimidine tract at their 5′ transcriptional start site, termed a 5′TOP, which has been shown to be essential for their regulation at the translational level (Volarevic, S. et al., Prog. Nucleic Acid Res. Mol. Biol. 2001, 65, 101-186). p70S6K dependent S6 phosphorylation is stimulated in response to a variety of hormones and growth factors primarily via the PI3K pathway (Coffer, P. J. et al., Biochem. Biophys. Res. Commun, 1994 198, 780-786), which may be under the regulation of mTOR, since rapamycin acts to inhibit p70S6K activity and blocks protein synthesis, specifically as a result of a down-regulation of translation of these mRNA's encoding ribosomal proteins (Kuo, C. J. et al., Nature 1992, 358, 70-73).
In vitro PDK1 catalyses the phosphorylation of Thr252 in the activation loop of the p70 catalytic domain, which is indispensable for p70 activity (Alessi, D. R., Curr. Biol., 1998, 8, 69-81). The use of rapamycin and gene deletion studies of dp70S6K from Drosophila and p70S6K1 from mouse have established the central role p70 plays in both cell growth and proliferation signaling.
The 3-phosphoinositide-dependent protein kinase-1 (PDK1) plays a key role in regulating the activity of a number of kinases belonging to the AGC subfamily of protein kinases (Alessi, D. et al., Biochem. Soc. Trans 2001, 29, 1). These include isoforms of protein kinase B (PKB, also known as AKT), p70 ribosomal S6 kinase (S6K) (Avruch, J. et al., Prog. Mol. Subcell. Biol. 2001, 26, 115), and p90 ribosomal S6 kinase (Frodin, M. et al., EMBO J. 2000, 19, 2924-2934). PDK1 mediated signaling is activated in response to insulin and growth factors and as a consequence of attachment of the cell to the extracellular matrix (integrin signaling). Once activated these enzymes mediate many diverse cellular events by phosphorylating key regulatory proteins that play important roles controlling processes such as cell survival, growth, proliferation and glucose regulation [(Lawlor, M. A. et al., J. Cell Sci. 2001, 114, 2903-2910), (Lawlor, M. A. et al., EMBO J. 2002, 21, 3728-3738)]. PDK1 is a 556 amino acid protein, with an N-terminal catalytic domain and a C-terminal pleckstrin homology (PH) domain, which activates its substrates by phosphorylating these kinases at their activation loop (Belham, C. et al., Curr. Biol. 1999, 9, R93-R96). Many human cancers including prostate and NSCL have elevated PDK1 signaling pathway function resulting from a number of distinct genetic events such as PTEN mutations or over-expression of certain key regulatory proteins [(Graff, J. R., Expert Opin. Ther. Targets 2002, 6, 103-113), (Brognard, J., et al., Cancer Res. 2001, 61, 3986-3997)]. Inhibition of PDK1 as a potential mechanism to treat cancer was demonstrated by transfection of a PTEN negative human cancer cell line (U87MG) with antisense oligonucleotides directed against PDK1. The resulting decrease in PDK1 protein levels led to a reduction in cellular proliferation and survival (Flynn, P., et al., Curr. Biol. 2000, 10, 1439-1442). Consequently the design of ATP binding site inhibitors of PDK1 offers, amongst other treatments, an attractive target for cancer chemotherapy.
The diverse range of cancer cell genotypes has been attributed to the manifestation of the following six essential alterations in cell physiology: self-sufficiency in growth signaling, evasion of apoptosis, insensitivity to growth-inhibitory signaling, limitless replicative potential, sustained angiogenesis, and tissue invasion leading to metastasis (Hanahan, D. et al., Cell 2000, 100, 57-70), PDK1 is a critical mediator of the PI3K signalling pathway, which regulates a multitude of cellular function including growth, proliferation and survival. Consequently, inhibition of this pathway could affect four or more of the six defining requirements for cancer progression. As such it is anticipated that a PDK1 inhibitor will have an effect on the growth of a very wide range of human cancers.
Specifically, increased levels of P13K pathway activity has been directly associated with the development of a number of human cancers, progression to an aggressive refractory state (acquired resistance to chemotherapies) and poor prognosis. This increased activity has been attributed to a series of key events including decreased activity of negative pathway regulators such as the phosphatase PTEN, activating mutations of positive pathway regulators such as Ras, and overexpression of components of the pathway itself such as PKB, examples include: brain (gliomas), breast, colon, head and neck, kidney, lung, liver, melanoma, ovarian, pancreatic, prostate, sarcoma, thyroid [(Teng, D. H. et al., Cancer Res., 1997 57, 5221-5225), (Brognard, J. et al., Cancer Res., 2001, 61, 3986-3997), (Cheng, J. Q. et al., Proc. Natl. Acad. Sci. 1996, 93, 3636-3641), (Int. J. Cancer 1995, 64, 280), (Graff, J. R., Expert Opin. Ther. Targets 2002, 6, 103-113), (Am. J. Pathol. 2001, 159, 431)].
Additionally, decreased pathway function through gene knockout, gene knockdown, dominant negative studies, and small molecule inhibitors of the pathway have been demonstrated to reverse many of the cancer phenotypes in vitro (some studies have also demonstrated a similar effect in vivo) such as block proliferation, reduce viability and sensitize cancer cells to known chemotherapies in a series of cell lines, representing the following cancers: pancreatic [(Cheng, J. Q. et al., Proc. Natl. Acad. Sci. 1996, 93, 3636-3641), (Neoplasia 2001, 3, 278)], lung [(Brognard, J. et al., Cancer Res. 2001, 61, 3986-3997), (Neoplasia 2001, 3, 278)], ovarian [(Hayakawa, J. et al., Cancer Res. 2000, 60, 5988-5994), (Neoplasia 2001, 3, 278)], breast (Mol. Cancer Ther. 2002, 1, 707), colon [(Neoplasia 2001, 3, 278), (Arica, S. et al., J. Biol. Chem. 2002, 277, 27613-27621)], cervical (Neoplasia 2001, 3, 278), prostate [(Endocrinology 2001, 142, 4795), (Thakkar, H. et al. J. Biol. Chem. 2001, 276, 38361-38369), (Chen, X. et al., Oncogene 2001, 20, 6073-6083)] and brain (glioblastomas) [(Flynn, P. et al., Curr. Biot. 2000, 10, 1439-1442)].
Mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP K2 or MK2) mediates multiple p38 MAPK-dependent cellular responses. MK2 is an important intracellular regulator of the production of cytokines, such as tumor necrosis factor alpha (TNFα), interleukin 6 (IL-6) and interferon gamma (IFNg), that are involved in many acute and chronic inflammatory diseases, e.g. rheumatoid arthritis and inflammatory bowel disease. MK2 resides in the nucleus of non-stimulated cells and upon stimulation, it translocates to the cytoplasm and phosphorylates and activates tuberin and HSP27. MK2 is also implicated in heart failure, brain ischemic injury, the regulation of stress resistance and the production of TNF-α (see Deak et al., EMBO. 17:4426-4441 (1998); Shi et al., Biol. Chem. 383:1519-1536 (2002); Staklatvala., Curr. Opin. Pharmacol. 4:372-377 (2004); and Shiroto et al., J. Mol. Cell Cardiol. 38:93-97 (2005)).
Published patent application U.S. 20070043045 relates to novel high-affinity thiophene-based and furan-based kinase ligands, useful for the treatment of diseases associated with the activity of protein kinases.
International Publication WO 2007/123269 relates to azolecarboxamide derivatives useful for treatment of lower urinary tract disease or various diseases accompanied by pain.
International Publications WO 2008/054701, WO 2008/054702 and WO 2008/054749 relate to 2-aminothiazole-4-carboxylic acid amides as protein kinase inhibitors useful for the treatment of diseases associated with the activity of protein kinases.
There is a need for effective inhibitors of protein kinases in order to treat or prevent disease states associated with abnormal cell proliferation. Moreover, it is desirable for kinase inhibitors to possess both high affinities for the target kinase as well as high selectivity versus other protein kinases. Small-molecule compounds that may be readily synthesized and are potent inhibitors of cell proliferation are those, for example, that are inhibitors of one or more protein kinases, such as CHK1, CHK2, VEGF (VEGF-R2), Pim-1, PDK-1, CDKs or CDK/cyclin complexes and both receptor and non-receptor tyrosine kinases.